Process and apparatus for treatment of mineral materials



June 6, 1939. B. M. amp ET AL PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet l Hi7. I

/NVEN TORS. Byron M B/rd AND Mac/r E flan/017171,

ATT'Y B. M. BIRD-El AL ,5 0

Or iginal Filed Jan. 2, 1935 15 Sheets-Sheet 2 ATTY June 6, 1939.

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL. MATERIALS Jul ze 6, 1939. B. M. BIRD ET AL R 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet s l/YVENTORS: Byron /zz. B/i'd -Ma c/v EhavQorf/v,

'' A-i-T Y B. M. BIRD ET AL June 6, 1939.

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 l5 Sheets-Sheet 4 O fNl/ENTORS: Byron M B/rd AND Mac/r E Haworf/a,

BY 44. 77' M,

ATT).

June 6, 1939. B. M. BIRD ET AL 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet 5 Byro/ Bird R n me Q .m v m U W? QT UT L. A Q m m m v mv MU 6H .m nun u g L g 4 fl||||| ll mw nu MW L1 1 31 El $1 rm u" 4 Lb. mv um mm 5. NF a5 15 u m .vv 3 4 5 .m v u 5 r m NW a6 .o P dom June 6, 1939. B. M. BIRD ET AL 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet 6 ATT'Y June 6, 1939. B. M. BIRD ET AL 2,161,500

, PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet v l Ellm 8 f/vvs/v TORS. Byron g B/kd A Mack E. Hawqirf/v,

June 6, 1939. B. M. BIRD ET AL PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet B h 5d wkw MT 7 .A NMNE W E 5. M m 175. 02%

ft m June 6, 1939. B. M. BIRD ET AL 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet 9 f N VEN TO R s By/"on M B/r'd Mac/r E Hawor-fh,

ATT'X June 6, 1939. M 3mg AL 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet 10 i 21% 7 jn uuufififin uln g gjlun lit! 1 k 7K /L 37 HEN HEHHE \V I 38 R1343 //-/v5/ /Tofi=s:

' Byron Q1 E/FQ Mac/\- E Hawonfh,

' BY 64 4, 777, M

June 6, 1939. B. M. BIRD ET AL PROCESS AND APPARATUS Eon TREATMENT OF MINERAL MATERIALS Original Filed Jan 2, 1935 15 Sheets-Sheet 11 Ealq. 15'

[NVENTOR;5: I

Byr'bn v A ND Mack EJ-raworfh,

r. I m.

ATT'Y June 6, 1939. 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS B. M. BIRD ET AL Original Filed Jan. 2, 1935 15 Sheets-Sheet l2 1 HIGH GRAVITY PARTICLES.

% INTERMEDIATE GRAVITY PARTICLES.

D LOW GRAVITY PARTICLES.

LARGER COAL.

L M C E m F HIG H GRAVITY MATERIAL.

LARGER COAL.

INTERMEDIATE GRAVITY MATERIAL.

E .m 3 Y z w m A N o o c c E m E F H HIGH GRAVITY MATERIAL.

[N VENTORS Byr'on M 5/71! AND Mac/v E. Haworfh,

ATT'Y June 6, 1939. B. M. BIRD ET AL 2,151,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet l3 IOOOO IOOOO GOOD 5 VELOCITY FEE-r PER Mmu-ra.

IOOO

Mean-1 DIAMETER OF PARTICLES |NCHES.

TERMINAL VELocrnEs \N Ana.

Ei q. 21

' Cunves A-B-"FREE SETTUNG' [NVENTOR 5- Culzv ES C- D JHINDERED sETTl-lNG Byron. y B/FC/ N Culevezs E-F :SUPER Hmosneo SETTLm'. Mac/r HaWOF/h,

BY GLM WW,

June 6, 1939. B|RD AL 2,161,500

PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet l4 DEDUSTER- 16 |Ol CLASSIFYING 5CREEN.

I04 LAUNDER.

/N \(ENTORS: Byron Q1 Bird Mac/r E Haworfh ATT'Y June 6, 1 939. B. M. BIRD ET AL PROCESS AND APPARATUS FOR TREATMENT OF MINERAL MATERIALS Original Filed Jan. 2, 1935 15 Sheets-Sheet 15 a m r Rm o w. n 7 N N Y N m c B M NwMW NE 5 5 no 4 m N I ww on n I 5 on K h w Q N, o m 4 r9 .2; m \FQ a a H. 0 mo. NQ H L A w 0 mo. W o .09 WW m9 me H 5. we 0 20 Q ATTY ' Patented June 6,1939

UNITED STATES PATENT OFFICE.

PROCESS AND APPARATUS FOR TREAT- MENT F MINERAL MATERIALS Ohio Application January 2, 1935, Serial No. es Renewed 0mm 13, 193-:

Claims. (01- 209-466) In ore and coal dressing and analogous operations, it is frequently desirable to subject the material to a process of concentration for the purpose of separating materials of various char- 5 acteristics, one from the other.

The present invention relates to a new and improved process of and apparatus for treating materials composed of mixtures of particles of different sizes, and of different specific gravities 0 which may or may not be of relatively wide range, whereby a concentration or separation of desired components substantially free from undesired components is obtained.

One of the objects of the present invention is 5 to effect a complete concentration or separation of component parts of a mass of material of relatively wide size range in accordance with the specific gravities of the various component parts, irrespective of size.

:0 A further object of the invention is to coordinate, properly, the fundamentalprinciples underlying the various conditions by which mobility in a bed of material may be produced, so that conditions herein termed super-hindered set- :5 tling are prevalent.

A still furtherobject of the invention is to effect concentration of the various fractions of materials found in a raw mined product, in-a single step or a series of steps, comprising strati- :0 flcation, isolation of a portion of the materials stratified in the lower strata, and removal of the concentrates in a continuous operation.

A more specific object of the invention is to combine the effects of mechanical agitation of i5 a bed of raw materials undergoing treatment, the flow of air upwardly through said bed, and the removal of certain fractions of the stratified material, in a continuous operation, to separate and classify the fractions of the raw material in a very efflcient manner.

A still further object of the invention is to provide an apparatus the design of which is in accordance with the underlying fundamental principles affecting super-hindered settling laws, the stratification of the bed, and the removal of the products of concentration.

Other objects of the invention will become apparent as the description proceeds, the invention being exemplified in the discussion and illustrations hereinafter set forth in detail, and in the combination and arrangement of parts shown in the accompanying drawings, and described in the following specification, the features of novelty of the invention being more particularly pointed out in the appended claims.

The present invention is based upon the observed behavior of a bed of materials made up of components of particles of diiferent sizes and different specific gravities, when subjected to combined mechanical agitation and upwardly di- 0 rected fluid currents.

Observance of the bed of materials made up of components of the character indicated above will demonstrate that modification of air flow (volume and/or velocities) or mechamcal agitation 5 or the elimination of either varies the results obtained.

In considering the probable phenomena which take place in the operation of our device and in the practice of the process or method of our 29 invention, observations indicate the following explanation of the action involved to be tenable, but it isto be understood that our method is not restricted by any particular theory of operation for, regardless of the exact action which takes place, practice has demonstrated the extremely desirable capabilities and high efliciency of said method and apparatus.

If a bed of materials is formed on a perforate screen, said bed containing particles of a rela- 3Q tively large size range and a relative large range of specific gravities, and a fluid, such as air, is forced upwardly through said bed at a substantially constant velocity, without mechanical agitation, the fluid velocity may be maintained sufflciently to maintain all of the particles in very fluid suspension. When this condition obtains and the largest particles of highest specific gravity are held completelyin suspension, the bed for practical purposes may be said to typify a condition of free-settling. Curves A-B of Fig. 21 are illustrative of interstitial air velocities capable of producing free-settling conditions for different size particles of different specific gravities. a 4

If this velocity is gradually reduced, a velocity will be reached at which the largest particles of highest gravity will just rest on the screen. This reduced fluid velocity gives a condition which is called hindered-settling. This condition is ob- 5o by curve C-D of Fig. 21 and represents a condition in which the lowest possible air velocities are employed to maintain substantially the whole bed mobile without mechanical agitation.

In the conditions of both free-settling and hindered-settling, excluding mechanical agitation from consideration, there is a tendency for all particles which are in mobility to assume positions in strata according to both size and specific gravity. That is, particles will tend to stratify according to size with the largest particles adjacent the screen and with the size of the particles decreasing upwardly. Likewise, there will be a tendency for the particles to stratify in accordance with specific gravities, with the highest gravity materials adjacent the screen and the lower gravity materials forming in strata decreasing upwardly. When mixed sizes and specific gravities are in a condition of free-settling, the largest particles of highest gravity material will be in the bottom stratum and the smallest particles of lowest gravity material will be in the upper stratum with mixtures of materials of different gravities and different sizes in all of the intermediate strata such that at any given level in the bed the particles of high specific gravity are smaller than those of low specific gravity. It is thus evident that with a bed of any appreciable size and gravity range, stratiflcation in accordance with specific gravity is impossible with continuous upward currents of air alone.

It is evident that the fluid velocity may be reduced below that required in hindered-settling" conditions so that none of the particles of highest specific gravity, irrespective of size, is held in suspension by the upward fluid currents. This reduced fluid velocity is employed in the method of our invention and is one requisite of the phenomena involved in "super-hindered-settling as hereinafter more completely described. The interstitial air velocities employed in a typical case may be represented by curves E--F of Fig. 21.

The above discussion pertains to conditions without mechanical agitation and, as indicated, where the fluid velocity was reduced to the point employed for "super-hindered-settling", a portion of the particles were out of suspension. This condition alone would not be satisfactory for separation of materials according to specific gravity for it is evident that to effect separation, the entire bed of materials within which the separation or stratification is to take place must be mobile, so that the particles are free to seek their proper stratum according to their density.

To provide the necessary fluidity of this bed, where this lowered fluid velocity is employed, mechanical agitation may be employed. Mechanical agitation may then be relied upon to supply mobility to a bed otherwise immobile and in the practice of the method of our invention this mechanical agitation is suflicient to keep substantially the entire bed mobile throughout its length and throughout the entire area and depth thereof, except for a volume of accumulated refuse formed in a depression or pocket where said refuse is withdrawn and where there is formed a bed of substantially immobile refuse of the highest gravity material of practically all sizes within the range treated.

This mechanical agitation not only maintains most of the bed fluid or mobile, but it has another important function in the stratification of the material according to specific gravity.

tained with the interstitial velocities illustrated It is known that if a bed of materials of different sizes and gravities, of any size range, is subjected to mechanical agitation without any fluid influences, the particles of a given specific gravity will tend to stratify according to size with the smallest particles on the bottom and the largest particles on the top, just the reverse of the tendency of said particles to stratify due to upward fluid currents. Mechanical agitation will also tend to stratify the particles according to specific gravities with the highest gravity particles on the bottom and the lowest gravity particles on the top. In this respect, the tendency is the same as that due to upward fiuid currents.

If mixed sizes and specific gravities are stratified, these two tendencies operate so that at any given level the particles of high specific gravity tend to be larger than those of low specific gravity. It is thus suggested that by taking advantage of both mechanical agitation and upward'fluid flow, and properly combining the two, it is possible to stratify a bed according to densities or specific gravities over a large size range. The size range that can be treated depends principally upon the difl'erence in the specific gravitles of the materials to be separated and upon the gradation of sizes thereof. A relatively large difference in specific gravities, and/or a uniform gradation of sizes favors a large size range of materials in one treatment.

However, the mere co-ordination of the proper air velocity and mechanical agitation is not alone suflicient to produce an ultimate separation of coal and refuse. It is necessary to combine these two forces to a degree that will not only effect mobility of the bed but so that the interstitial velocities will preferably be just below those required to suspend the smallest particles of refuse, whereby said smallest particles of refuse may pass downward through the interstices to the lower-strata of the bed. The above described conditions maintain during the longitudinal travel of the particles from a position where they are first subjected to treatment to a position where they are finally separated, along which path they are free to move and seek their positions as determined by the fluid flow and mechanical agitation, yet the combined effect of the mechanical agitation and fluid flow is so controlled that adjacent the end of travel of the particles an isolated bed of immobile refuse can form, across which the mobile bed extends, which immobile bed is formed of compact particles of the highest gravity particles of substantially all sizes within the treated range and is thus of such density that particles of lower or intermediate gravity material cannot penetrate said bed. This bed of immobile refuse preferably has a large surface, and extends rearwardly of the refuse withdrawal chute for an appreciable distance 'whereby vibrations imparted to the deck will be transmitted through said immobile bed as though it were a rigid part of the deck, and effect an efficient transfer of mechanical agitation to the mobile bed of material thereabove. Said immobile bed of refuse should also be maintained at substantially constant depth in any one pocket, after it is properly formed. This particular immobile bed formation will be discussed more in detail in connection with our method as carried out by the hereinafter described apparatus.

While these general principles are applicable to ore dressing generally, they are specifically applied in the present invention, for illustrative purposes, tothe treatment of coal. for the purpos e of obtainingagcoalof' desired ash content freefro nthe irnpuritiesusually associated with coal. For efficient operation, these impurities must be removed with little or no coal losses in the refuse.

Other objects of the invention will appear hereinafter, the novel. features and combinations being set'forth in the appended claims.

a An apparatus by means of which the present process may be carried out is illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevation of the coal cleaning apparatus;

Fig. 2 is a plan view thereof;

Fig. 3 is a fragmentary side elevation of the apparatus of Fig. 1;

Fig. 4 is a continuation of Fig. 3, Figs. 3 and 4 having been split to accommodate the views to the respective sheets of drawing;

Fig. 5-is a fragmentary vertical section taken along the longitudinal axis of the apparatus shown in Fig. 2;

Fig. 6 is a continuation of Fig. 5, showing the remainder of the apparatus, Figs. 5 and 6 having been split to accommodate the views to the respective sheets of drawing;

Fig. '1 is a transverse section of the apparatus, taken on the line 'I-l of Fig. 3;

Fig. 8 is a transverse section of the apparatus on the line 88 of Fig. 4;

Fig. 9 is a transverse section through one of the refuse ejectors, the view being taken on the line 99 of Fig. 3;

Fig. 10 is a fragmentary longitudinal sectional view of the apparatus, illustrating diagrammatically the charging of material, such as coal onto the apparatus and the flow of the materials along the apparatus, together with the stratification of the materials of the bed and separation of the heaviest gravity components therefrom;

a Fig. 11 is a continuation of Fig. 10, showing the continuation of the separation of the strata of the bed and final discharge of clean light gravity products from the apparatus;

Fig, 12 is a plan view of a preferred construction of a deck supporting member, illustrating certain details of the arrangement of the air distribution chambers;

Fig. 13 is an elevation of the structure shown in Fig. 12;

Fig. 14 is a plan view of the deck showing a preferred arrangement of the air distribution chambers;

Fig. 15 is an elevation of the structure shown in Fig. 14;

Fig. 16 is a sectional view of parts of the drive mechanism for obtaining variable drive speeds;

Fig. 17 is a view similar to Fig. 16, but showing the parts in somewhat different relative positions;

Figs. 18, 19 and 20 are vertical sections through the bed taken on the lines l8-|8, I9l9 and 20-20 of Fig. 10, respectively, showing the in creasing thickness of the bed and condition of stratification as the material moves to the first discharge chute;

Fig. 21 illustrates, by means of graphs, comparative interstitial air velocities that might be employed for given sizes of particles, with the velocities required to sustain those particles in a condition of free-settling, a condition of hindered-settling, or a condition of superhindered-settling", depending on t desired gravity separation;

Fig, 22 illustrates a diagrammatic flow sheet of the complete process; 1 l ;--Fig. .123 is a side; elevation,- similar-toFlgl,

showing the table oscillatable on rocker arms instead of the rollers of Fig. 1; and

Fig. 24 is a section through the feed mechanism taken on line 2424 of Fig. 10.

Referring more particularly to the drawings, it will be noted that in the illustrated form of apparatus, a main frame A supports a table'or launder B comprising a plurality of sections C, D and E, each of which is provided with a pervious upper surface C and refuse draw outlets 3!, Ma and 3"), respectively. The frame and launder B as illustrated slope downwardly from the feed end to the discharge end so that the materials being treated flow along the launder at a rate of travel dependent upon-the degree of mobility produced and the slope or inclination of the launder. Side walls extending along each side of the pervious deck surface confine the material to a straight flow, there being no change in general direction of flow except where the separation of refuse takes place.

-A drive mechanism generally indicated at F is provided for reciprocating the launder B in a plane parallel to the main frame A, the frequency and length of the strokes being such that the proper degree of mobilitywill be produced in a bed of material fed to the launder from feeding mechanism G due to mechanical agitation in cooperation with the aeration thereof.

Aeration of the bed completes mobility or fiuidizes most of the bed confined within the launder side walls so that stratification may take place. It will be noted from reference to Figs. 10 and 11 that the bed of materials is relatively thin at the feed end of each section or pocket and that it gradually increases in thickness as it approaches the point of refuse withdrawal. In order to maintain substantially the same degree of fluidity through the entire travel of the material, except for an immobile bed of refuse which accumulates adjacent each refuse withdrawal pocket, it is necessary to sectionalize the launder beneath the material supporting surface and control the flow of air (volume and pressure) to each section. We have provided air flow control devices generally indicated at H which give the operator complete control of the air currents and permits him'to maintain the proper degree of mobility throughout the length of the bed to insure complete stratification of the kind above referred to.

Each section C, D and E is provided with refuse ejector mechanism positioned substantially adjacent the deepest portion of the pocket, within which forms an immobile bed of refuse, which mechanism is controllable for continuous or intermittent operation by mechanism generally indicated at J for withdrawing the refuse as it accumulates and thereby maintaining said immobile bed of refuse-of a desired quantity. Ad-

jacent each of saidpockets 28, 29 and 30, there is also provided a plurality of longitudinally extending riflles 30a which extend across the refuse discharge openings 3|, 3m and 31b. Short riflles 30b also extend rearwardly from the refuse discharge openings. These riflles 30a and 30b cause the refuse to become packed therebetween and increase the friction between the deck and the bed of immobile refuse and insure their movement in unison. They also prevent scouring out of the refuse by the mobile bed which moves into a subsequent section. The spacing of the limes 33a and 30b is normally decreased in each succeeding pocket down the deck. That is, the riflles in pocket 30 are very closely spaced, those in'pocket 23 less closely spaced and those in pocket 23 spaced the greatest amount. This takes care of the reduced density of the refuse in each of said pockets. That is, thed efuse in pocket 23 will be the highest gravity, that in pocket 23 lesser gravity and that in pocket "the lowest gravity. The lower the gravity of the refuse, the greater the friction necessary to maintain immobility in the refuse bed. In some cases, where the material has a high coeflicient of friction or the deck surface is very.

rough, the riilles may be omitted.

The main frame A not only supports the launder B for reciprocatory movement but carries the drive mechanism F, the air now control device H and the ejector drive mechanism J.

The main frame A comprises the channels I and la, held together in spaced relation by end cross members 2, intermediate cross members 3 and the ejector drive support frames 3, to form a rectangular open frame. The frame A is pivotally supported at the feed end on a shaft 4 journaled in bearings I secured to a support 6 of sufllcient height to permit the frame to carry the air flow control device H and the refuse drive mechanism J in proper spaced relation to the launder and above the floor. At the foot or discharge end, the main frame A is supported upon screw jacks l, or other suitable devices, by means of whichthe slope or inclination of the main frame and launder may be adjusted.

The launder B is supported above the main frame A for reciprocatory movement in a plane, always parallel thereto on rollers 3, mounted in brackets 3 attached to the channels I and la, as illustrated in Fig. 1 or, as illustrated in Fig. 23, by rocker arms I05 pivotally connected as at It and Ill to brackets I03 and I0! which are secured to the main frame A and launder B, respectively. If the rocker arm support be employed, the arms should be set so that the vertical component of movement is at a minimum.

Drive mechanism F for the launder cornprises a motor lil mounted upon a motor base ll of the slide rail type, which is rigidly connected to the frame A, and adjustable upon the slide rails by hand wheel l2, in a well-known manner. A V-belt drive mechanism comprising the drive pulley l3 (Fig. 3), fixed to the armature shaft ll of the motor I0, is connected by a belt l5 to a driven pulley I 3 keyed to the crank shaft l1, journaled in bearings I3, I31: and l3b, Fig. 2, attached to the channels I and I a, through a supporting block l3a. Oscillation or reciprocation of the launder B by the power of the motor i0 is accomplished through the medium of a connecting rod ll eccentrically journaled at 20 on the crank shaft I1 and at its opposite end pivotally connected as at 2| to the launder B.

75. Referring to Figs. 2, 16 and 17, it will be noted that adjustment of the drive pulley is accomplished-by moving the motor ll back and forth by handwheel I 2, which correspondingly eflects the tension of belt it. Thus when the motor I0 is pulled to tension the belt IS, the belt crowds between the discs 22 and 23 of the drive pulley i3, disc 23 being movable on the pulley hub 24 relatively to the disc 22. Spring 25, positioned between the movable pulley disc 23 and nut 28 threaded, as indicated at 21, on the end of the hub 24, is thereby compressed, and returns; upon release oftension on the belt l5, to force the discs 22 and 23 together'and to force the belt from the inner position of Fig. 17 to the outer position of Fig. 16. The compression spring 25 on the'sliding disc 23 assures suflicient friction on the belt to transmit the rated load of the motor at all speeds. Nut 23 permits regulation of spring tension. The belt is driven faster when in the outer position of Fig. 16 than when in the inner position of Fig. 17, so that corresponding adjustment of the speed of the shaft l1 and, therefore, of the connecting rodl9 may be effected.

Referring particularly 'to Figs; '7, 8 and 9, it will be noted that the launder main frame comprises the side sills 33 and 34 joined together and held in spaced relation by end cross members, not

shown, to make a rigid rectangular frame structure. Positioned between the side sills 33 and 34 and extending along the bottom edges thereof in spaced relation, is a plurality of assembled units L of air distribution chambers such as illustrated in Figs. 12 and 13. It will be noted from reference to Figs. 5, 6, 7, 8, 9, l0 and 11 that units L project below the bottom edge of the side sills 33 and 34 leaving a space at the top thereof.

Deck members K, such as illustrated in Figs. 14 and 15, are positioned above the units L, all of which are spaced longitudinally of the launder to provide openings 3| 3 la and 3lb, respectively, at adjacent ends in which are positioned refuse draw chutes. All of the above mentioned elements, units L, K and refuse chutes, are fastened to one another and to the side sills 33 and 34 to make the assembly rigid and substantial.

It will be noted that the upper surface of each of the deck units K has a contour which when in assembled relation forms the pockets 23, 23 and 30,, respectively, each of which comprises the gradually sloping curved forward portion ill,

' the relatively deep portion H and the rearward upwardly curved portion l2. This surface is covered by a perforated screen plate 51 having the proper percentage of open area to distribute the currents of air evenly over the entire surface. While not so illustrated in Figs. 6 and 9, it is to be understood that the plate 51 is perforated throughout its length and breadth.

We have described the effect of mechanical agitation upon a bed or burden of material; if a flat inclined surface is employed, the material will travel along said inclined surface en masse in the direction of inclination. However, in following the present process, it is necessary to collect and retard the materials forming the lower strata of the stratified bed of materials. For this reason, the depression or relatively deep portion II is formed. The curved portion I2 being of sufficient rise to retard the flow of the lower strata forms a bed with certain limits of vertical depth. The outlets, 3|, 31a and 3ib, from the bed to the refuse chutes, it will be noted, are positioned at 1 or near the deepest portion of the bed or pocket and extend entirely across the launder.

We have found by employing empirical methods that mechanical agitation to transfer the maximum amount of energy and thereby to produce the greatest degree of mobility in the mobile bed due to said mechanical agitation is accomplished by movement of the launder at from 225 V to 275 oscillations per minute and from to A,"

go/will be noted that under "super-hindered-settling conditions much lower velocities are employed.

It will be noted from reference to Figs. 10 and 11 that the depth of the bed or burden is changing continuously throughout the entire length of travel of the material and tends in any given compartment 'to increase in the direction of travel; Due to the friction of the immobile bed of refuse, the depth of the mobile bed thereabove may, in some instances, tend to increase but this is not harmful. Generally, however, the mobile bed has a nearly uniform depth over its entire length of travel in any given compartment. The interstitial velocities through the upper strata of the bed must remain substantially constant for practically all depths of refuse bed. It is well known that in air operated apparatus an increased depth of bed requires higher upward velocities to maintain mobility throughout the entire depth of the bed. However, in our invention, this is not necessary, for the refuse bed accumulating adjacent the refuse draws is not maintained ina mobile condition.

The increase in depth of refuse bed increases the resistance to flow of air and will increase the interstitial velocities in the lower part of the bed due to its greater compactness and, since a single fan or blower element is usually employed to supply the entire volume of air, there must be provided air control devices in connection with.

each transverse section of the launder to provide increased pressure to maintain said volume constant. By empirical methods, we have found that for practical purposes, it is necessary to provide separate air distribution chambers for each M4 to change in depth of bed.

As was mentioned previously, the table is provided with a series of sections C, D and E providing pockets indicated at 28, 29 and 30, for the purpose of withdrawing successive strata of the bed. These pockets are provided, respectively, at substantially their deepest portions, with refuse discharge chute openings 3|, 3|a. and 3"), each chute being preferably made of a casting having an offset 32, the purpose of which will be explained hereinafter. These chutes are affixed to the side sills 33, 34 of the table B, providing additional stiffening means and definitely spacing the pockets or sections. The chutes extend transversely entirely across the table.

Referring to Figs. 12 and 13, the units L comprise the longitudinal side plates 35, end plates 33 and 31, bottom plate 38, transverse plates 39 and longitudinal plates 48, all of which may be of steel or wood securely held together, or the unit may be of cast metal, such as aluminum, as conditions may dictate. Apertures 4| are provided in the bottom plate 38 for reception of the air diffusion elements 42, the side walls of which are perforated, as indicated at 43 (Fig. 5) for passage of air, the tops 44 being closed. Each of the air diffusion elements 42 is provided with a flange 44a which by means of bolts. or the like may be securely fastened to the bottom plate 38, there being a packing 45 between the flange 44a and the bottom plate 38 to seal against air leaka e. The open ended projections 46 of the air diffusion elements 42 are received in flexible hose connections 41a, the connection being sealed by cementing or the like, and connect with air supply pipes leading from manifolds 41. Each manifold is connected by pipes 48 to the main air supply chamber 50, there being provided valves 49 in the pipes 48 to control the flow of air to each transverse section -of the launder. The flexible pipe connections 47a enable the launder to oscillate or reciprocate with respect to the stationary main supporting frame A. Additional air control valves 9| (Fig. 7) are positioned within each tube 41a at its point of connection with the manifold' ll so that flow of air to each portion of any transverse section may be controlled.

In Figs. 5 and 6, it will be noted that the end plates .36 and 3'! are fixed to the chute walls with felt packing 5| between the points of contact.

The deck frame unit, generally indicated at K, is illustrated in Figs. 14 and 15 and comprises the side members 52, end cross members 53 and 53a, intermediate cross members 54, some of which are of greater height than others, and longitudinal members 55. All of these members are preferably made of hard wood for strength and lightness. The relative diiference in height of the cross members may be modified to conform to the contour of the deck surface required. It will be noted that the longitudinal members 55 are staggered so that there will be no continuous paths longitudinally of the launder or in the direction of flow of material above which the bed might not be aerated.

In assembling the device, the units K are positioned between the side sills 33 and 34 above the air distribution units L with the transverse members 54 of the decks in alignment with the transverse member 39 of the air distribution units (Fig, 5). All abutting edges of these respective units K and L are sealed against air leakage with strip felt or other suitable packing 51a. The perforated deck plate 51 is securely fastened to the upper edges of the longitudinal and transverse members of the deck units L by means of small wood screws, closely spaced to prevent air leakage from one section to another. The longitudinal members 62 (Figs. 14 and 15) of the deck units L are provided to support the deck plate 51 between the members 54 and add to the strength of the deck frames.

It is also to be noted that the lower edges of members 32 are double beveled to reduce to a minimum their interference with the passage of air upwardly through the deck plate 51.

After the deck units are assembled in proper relation to the air distribution chamber units to form the sections C, D and. E with the slotted openings 3|, 3m and 3|b, respectively, of the proper width, the trough plates 58 which are provided with longitudinally extending angles 59 may be clamped by means of bolts 60 to angles 6| extending along the top edge of the sills 33 and 34; this forces the abutting edges of the deck units 

